Guns. Muggle weapons. Jesus, Mary, and Joseph, the woman was clearly a danger to herself and others.
"Tha's my job. Yeh leave it to me. It's what I get paid to do. Yeh, on the other hand, get paid to play Quidditch. Not snoop around crime scenes and capture 'bad guy wizards'."
And if a Muggle farmer came along, Lance would simply make up an explanation and, if that didn't work, Obliviate them.